Synthesis and Characterization of Novel Oxotechnetium (<sup>99</sup>Tc and <sup>99m</sup>Tc) and Oxorhenium Complexes from the 2,2‘-Bipyridine (NN)/Thiol (S) Mixed-Ligand System

Papachristou, Maria; Pirmettis, Ioannis; Tsoukalas, Charalambos; Papagiannopoulou, Dionysia; Raptopoulou, Catherine P.; Terzis, Aris; Stassinopoulou, C. I.; Chiotellis, E.; Pelecanou, Maria; Papadopoulos, Minas

doi:10.1021/ic034368j

Cited by 14 publications

(10 citation statements)

References 33 publications

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“…The infrared spectra of the complexes (KBr disk) show the characteristic of Re⋮O band, ranging from 978 to 947 cm -1 . These values are within the range for the Re⋮O stretching frequencies reported in the literature. , …”

Section: Resultssupporting

confidence: 87%

Studies of C−S Bond Cleavage Reactions of Re(V) Dithiolates: Synthesis, Reactivity, and Mechanism

Ellern

Espenson

2005

J. Am. Chem. Soc.

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A series of rhenium(V) complexes, [(X)(ReO)(dt)(PPh(3))] and [(o-SC(6)H(4)PPh(2))(ReO)(mtp)], were prepared to explore electronic effects on the C-S cleavage reaction that occurs upon reaction with PAr(3) at ambient temperature [where X = S(C(6)H(4)-p-Z) (Z = OMe, Me, H, F, Cl), OPh, Cl, and SC(2)H(5), and dt is the chelating dithiolate ligand derived from 2-(mercaptomethyl)thiophenol, 1,2-ethanedithiol, 1,3-propanedithiol, 1,3-butanedithiol, and 2,4-pentanedithiol]. The scope and selectivity of the C-S activation were examined. The C-S bond cleavage to form metallacyclic Re(V) complexes with a ReS core occurs only for the complexes with mtp and pdt frameworks and X = SAr and SC(2)H(5). The difference in reactivity is due to the different donating abilities of ancillary and dithiolate ligands, especially their pi-donating ability, which plays a critical role in C-S activation. The kinetics of the C-S activation process was determined; nucleophilic attack of PPh(3) on the oxo group of the Re(V)O core appears to be the rate-controlling step. The reaction is accelerated by electron-poor ArS ligands, but is unaffected by the substituents on phosphines. A detailed mechanistic study is presented. The results represent a rare example of migration of alkanethiolate leading to the formation of alkylthiolato complexes.

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Section: Resultssupporting

confidence: 87%

Studies of C−S Bond Cleavage Reactions of Re(V) Dithiolates: Synthesis, Reactivity, and Mechanism

Ellern

Espenson

2005

J. Am. Chem. Soc.

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“…The ReO stretch of both isomers of 3 − 5 occurs at 950, 951, and 945 cm -1 , respectively, well within the range of oxorhenium complexes with aminothiolate ligands. , …”

Section: Resultssupporting

confidence: 52%

“…The oxotechnetium TcO[NN][S] 3 analogue 6 , having 4-methylthiophenol as coligand, was prepared using 99 Tc−gluconate as precursor. Its TcO stretch occurs at 918 cm -1 , and the approximately 30 cm -1 difference from the oxorhenium complex 4 is a typical one between analogous oxotechnetium and oxorhenium complexes. , …”

Section: Resultsmentioning

confidence: 97%

Oxorhenium(V) and Oxotechnetium(V) [NN][S]₃ Complexes of 2-Phenylbenzothiazole Derivatives

et al. 2005

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The reaction of 2-(2'-pyridyl)benzothiazole, [NN], with the ReO(V)(3+) and TcO(V)(3+) cores in the presence of thiophenols, [S] (RC(6)H(4)SH, R = H, 4-CH(3), 4-OCH(3)), as coligands led to the isolation of hexacoordinated complexes of the MO[NN][S](3) type (M = Re, Tc). In all cases, two geometric mer isomers were formed, as evidenced by NMR spectroscopy and confirmed by X-ray crystallography. In both isomers, the coordination geometry about the metal ion is a distorted octahedral defined by the two nitrogen atoms of the bidentate ligand, the three sulfur atoms of the monodentate thiols, and the oxygen atom of the oxo group. The apical positions of the octahedron are occupied by the oxygen of the oxo group and, in one of the isomers, the nitrogen of the pyridyl moiety of 2-(2'-pyridyl)benzothiazole, while, in the second isomer, the imine nitrogen of 2-(2'-pyridyl)benzothiazole. The complexes are stable, neutral, and lipophilic. Complete (1)H and (13)C NMR assignments are reported for all complexes. The synthetic reaction was also successfully transferred at the technetium-99m tracer level by ligand exchange reaction using (99m)Tc-glucoheptonate as precursor in the presence of 2-(2'-pyridyl)benzothiazole and 4-CH(3)C(6)H(4)SH. The structure of the technetium-99m complex was established by high-performance liquid chromatographic comparison with the analogous oxotechnetium and oxorhenium complexes. The 2-(2'-pyridyl)benzothiazole ligand serves as a preliminary model for 2-(4-aminophenyl)benzothiazole, which possesses interesting properties for the development of technetium and rhenium radiopharmaceuticals for tumor imaging and/or radiotherapy as well as in vivo diagnosis of Alzheimer's disease.

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“…Alternative positioning of the NN ligand 3 trans to the oxometal center would limit to some extent the kinetic freedom of the side chain. The preference of the sp 2 nitrogen donor atom of the NN bidentate ligand to occupy the apical position trans to the oxygen of the oxorhenium(V) core has been observed in all other monooxo octahedral oxorhenium and oxotechnetium MO[NN][X] 3 complexes, with NN being 2,2‘-bipyridine, 20a,b biimidazole,20b 2-(2‘-pyridyl)benzothiazole, 20c,d 2-(2‘-pyridyl)benzoxazole,20d or diazabutadienes 20e and X being monodentate chlorine or thiophenol ligands.…”

Section: Resultsmentioning

confidence: 98%

Synthesis and Characterization of Novel “3 + 2” Oxorhenium Complexes, ReO[SNO][NN]

et al. 2006

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The present paper deals with the synthesis and structural characterization of novel neutral oxorhenium(V) complexes of the general formula ReO[SNO][NN]. The simultaneous action of the tridentate SNO ligand, N-(2-mercaptoacetyl)glycine (1), and the bidentate NN ligand, N-phenylpyridine-2-aldimine (2), on ReOCl3(PPh3)2 leads to the formation of two isomers 4a and 4b of the general formula ReO[SNO][NN], as a result of the different orientations of the NN ligand. In both cases, the SNO donor atoms of the tridentate ligand occupy the three positions in the equatorial plane of the distorted octahedron, whereas the oxo group is always directed toward one of the apical positions. In the first isomer, 4a, the imino nitrogen of the NN ligand occupies the fourth equatorial position and the pyridine type nitrogen is directed trans to the oxo group, while in the second isomer, 4b, the imino nitrogen of the NN ligand occupies the apical position trans to the oxo group and the pyridine type nitrogen completes the equatorial plane of the distorted octahedron. The [SNO][NN] mixed-ligand system was applied in the synthesis of the oxorhenium complex 5 in which the 1-(2-methoxyphenyl)piperazine moiety, a fragment of the true 5-HT1A antagonist WAY 100635, has been incorporated in the NN bidentate ligand (NN is N-{3-[4-(2-methoxyphenyl)piperazin-1-yl]propyl}pyridine-2-aldimine). In this case, high-performance liquid chromatography and NMR showed the existence of one isomer, 5, in which the pyridine nitrogen is trans to the oxo core, as demonstrated by crystal structure analysis.

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Synthesis and Characterization of Novel Oxotechnetium (⁹⁹Tc and ^99mTc) and Oxorhenium Complexes from the 2,2‘-Bipyridine (NN)/Thiol (S) Mixed-Ligand System

Cited by 14 publications

References 33 publications

Studies of C−S Bond Cleavage Reactions of Re(V) Dithiolates: Synthesis, Reactivity, and Mechanism

Studies of C−S Bond Cleavage Reactions of Re(V) Dithiolates: Synthesis, Reactivity, and Mechanism

Oxorhenium(V) and Oxotechnetium(V) [NN][S]₃ Complexes of 2-Phenylbenzothiazole Derivatives

Synthesis and Characterization of Novel “3 + 2” Oxorhenium Complexes, ReO[SNO][NN]

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Synthesis and Characterization of Novel Oxotechnetium (99Tc and 99mTc) and Oxorhenium Complexes from the 2,2‘-Bipyridine (NN)/Thiol (S) Mixed-Ligand System

Cited by 14 publications

References 33 publications

Studies of C−S Bond Cleavage Reactions of Re(V) Dithiolates: Synthesis, Reactivity, and Mechanism

Studies of C−S Bond Cleavage Reactions of Re(V) Dithiolates: Synthesis, Reactivity, and Mechanism

Oxorhenium(V) and Oxotechnetium(V) [NN][S]3 Complexes of 2-Phenylbenzothiazole Derivatives

Synthesis and Characterization of Novel “3 + 2” Oxorhenium Complexes, ReO[SNO][NN]

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Synthesis and Characterization of Novel Oxotechnetium (⁹⁹Tc and ^99mTc) and Oxorhenium Complexes from the 2,2‘-Bipyridine (NN)/Thiol (S) Mixed-Ligand System

Oxorhenium(V) and Oxotechnetium(V) [NN][S]₃ Complexes of 2-Phenylbenzothiazole Derivatives